MTS is the largest mobile operator in Russia and CIS

Commonwealth of Independent States

The Commonwealth of Independent States is a regional organization whose participating countries are former Soviet Republics, formed during the breakup of the Soviet Union....

 with over 102,4 million subscribers as of 31 December 2009.

Having started in the Moscow license zone in 1994, МТS in 1997 received licenses for further areas and began expansion, later entering other countries of the CIS. On October 31, 2008, Vodafone

Vodafone

Vodafone Group Plc is a global telecommunications company headquartered in London, United Kingdom. It is the world's largest mobile telecommunications company measured by revenues and the world's second-largest measured by subscribers , with around 341 million proportionate subscribers as of...

 announced a partnership deal with MTS, whereby Vodafone services will be available to MTS subscribers and both companies have noted the potential for more efficient purchasing.
The MTS wireless network operates using the GSM standard.